1. Field of Invention
The present invention relates to a keyboard device. More particularly, the present invention relates to a rotatable keyboard device.
2. Description of Related Art
The convertible tablet PC (personal computer) integrates a normal notebook and tablet PC in a shell. An easy way to convert a tablet PC from one operating status (such as normal notebook) to another operating status (such as tablet PC) is to directly rotate the display unit around the hinge to cover the base. Rotating the display unit uncovers the keyboard side of the base but leads to easy damage and incorrect pressing of the keyboard device.
Another method to convert the operating status of a tablet PC requires several steps. FIG. 1a˜1d shows a series of continuous operation diagrams of a traditional convertible tablet PC 100. FIG. 1a shows a traditional convertible tablet PC 100 comprising a display unit 110, a base 130 and a hinge apparatus 120, wherein the base 130 is a host or a server. First, the angle between the display unit 110 and the base 130 must be large enough; second, the display unit 110 must be rotated 180 degrees along a preset rotation direction “a” to make the front face 112 of the display unit 110 face backward and the back face 114 of the display unit 110 face forwards as shown in FIGS. 1b and 1c; and finally, the display unit 110 must be pushed down in the rotation direction “c” to cover the base 130 as shown in FIG. 1d. To convert the tablet PC 100 back to its original operation status (normal notebook), a user inverses the steps above.
The main disadvantage of a traditional convertible tablet PC 110 is that these conversion steps are too complicated to use for those who are not familiar with a notebook or tablet PC.
Besides, during the second step, while rotating the display unit 110 180 degrees, the display unit 110 can only be rotated in one direction, clockwise or counterclockwise, depending on the hinge apparatus 120 (for the foregoing example, rotation direction “a” is allowed while rotation direction “b” is not allowed). In other words, the user has to remember the preset rotation direction when rotating the display unit 110 or the hinge apparatus 120 may be damaged. To solve the problem, a user could apply a little force first to test which direction is correct, however, the little force repeatedly produced over a long period would still cause damage to the hinge apparatus 120.